The present invention relates to an armature and a manufacturing method therefore, and a DC motor.
A general DC motor with brushes is provided with a plurality of coils wound on a core and a commutator having a plurality of segments connected electrically to these coils, and the core and the commutator are fixed on a rotary shaft so as to be arranged along the axis of the rotary shaft. In a DC motor disclosed, for example, in Japanese Laid-Open Patent Publication No. 2003-299292, the end portion of a conductor forming the coil is engaged with a claw portion provided on a segment, and thereby the coil is connected electrically to the segment.
For the DC motor described in the above publication, a step is required in which after the coils have been wound on the core, the end portion of the conductor forming each coil is moved to the position of the claw portion of segment and is engaged to the claw portion. This requirement increases the number of steps for manufacturing the DC motor. Also, in order to enable the work for engaging the end portion of the conductor to the claw portion to perform smoothly, the core on which the coils are wound is arranged so as to be separate by a predetermined distance in the axial direction from the commutator. However, this configuration increases the size in the axial direction of the DC motor.
On the other hand, in a DC motor disclosed in Japanese Laid-Open Patent Publication No. 2004-88902, a columnar recess is formed in the core, and a part of the commutator is accommodated in this recess. Therefore, the size in the axial direction of the DC motor can be decreased. In the case where such a configuration is adopted, however, it seems that a winding step for winding the coils on the core and a joining step for joining the coils to the commutator need to be performed in the state in which the core and the commutator are mounted on the rotary shaft so that the axial positional relationship that does not hinder the winding step and the joining step, and subsequently, the commutator needs to be moved in the axial direction with respect to the rotary shaft so that the axial positional relationship of the core and the commutator becomes the positional relationship at the time of completion of motor. That is to say, it seems that it is necessary to perform a step in which the commutator is moved in the axial direction with respect to the rotary shaft at least a total of two times before and after the winding step and the joining step. Therefore, the number of steps for manufacturing the DC motor increases inevitably. Also, if the commutator is moved in the axial direction with respect to the rotary shaft after the joining step, there is a possibility of deforming or damaging the joint portion between the coil and the claw portion, thereby decreasing the reliability of the joint portion.